Battery Bank to Power Lunchwagon's Mobile Kitchen

System

I am completely new to, and thus quite ignorant of the concept of using batteries as a significant source of power, and even more naive regarding recharging using solar panels... so any help and patience will be greatly appreciated!

I am starting up a lunchwagon (mobile food concession) on Maui (specifically Lahaina), operating out of a 24' long X 8' wide FedEx-style truck.  My truck has a full kitchen, including refrigerator, freezer, coffee maker, small hot water heater, water pump, microwave, blender, lights,...  If I add up all of the appliance's watt usage, as though I were buying a generator to power the kitchen, it totals ~9,000 watts.  Not all appliances will be operating all of the time (microwave, water pump, etc.).  I plan to be operating 6 hours daily, and would like to recharge the batteries, at least initially, using an AC charger at home overnight.  Eventually, I would love to be able to sell food that was not cooked using electricity generated by the island's generator which burns diesel that people die for - rather I'd like to incorporate solar power into the equation.   A 10,000 watt generator is simply too big, too loud, and too polluting to be an option.

My questions:

1)  Is a bank of deep cycle batteries a practical solution to my energy needs?

2)  What battery is right for my needs?

3)  How many batteries would I require so as to not overly discharge the batteries?

4)  What other equipment would this AC recharging battery bank system require?

5)  How much would this all cost, don't forget I'd have to get the batteries, etc. to Maui?  How long?

6)  Would it be practical to mount PV panels on the roof (~22' X 8') of my lunchwagon, and be charging while actually at work and 
     drawing energy from the batteries (is this possible?)?

Thanks to any who might be able to assist me, I greatly appreciate it!!

crewzer

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Shimyapu,

A noble idea, but current technology limitations may be a challenge. I quickly estimated that you’d need a PV array rated at 8,000 W (STC), and the PV array and batteries together would weight ~4500 lbs.

So, before we go any further, let’s consider a hybrid approach typically used in RV applications. How do you feel about using LP to power your stove, fridge, freezer and water heater?

FYI: Solar radiation data for your “neck of the woods: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/sum2/22516.txt

More later,
Jim / crewzer

mike95490

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Use a solar heat collector on the roof for your hot water needs, or at least to preheat the water.

Forget about trying to haul 2 tons of battery bank around, you could get away with a half dozen batteries, for limited use.

As to the surface area of your rooftop, you likely have pop-up vents to get the hot air from the kitchen out, so you can't obstruct those with panels. Are you able to park in a full sun location while cooking/serving ? Maybe converting your tilt up side windows, you could add panels to them to collect more power. A 200 W panel is 65" x 40" (2600 si) giving 0.07692 watts per sq inch.
Your roof is 24x8 = 288" x 96" ( 27648si ) Completely covering your roof, could possibly produce 2.1KW, but more likely 1.5KW under normal conditions. (it's early, and my math could be way off here)

Deep freeze your food off the grid (set control 15 deg colder than normal) and try Dry Ice while mobile, to keep stuff frozen.

Time sharing your power, if microwave is on, all others = off. That way, you don't need to power EVERYTHING at once.

Skylights for most of the lighting.

Use vehicle to recharge while re-locating, or add an aux alternator for fast recharging. 28V is suggested, for a 24V battery bank

I'm sure someone will think of something else, but use propane for as much heating as possible. Propane fridges are really slow to recover losses, and may not keep up with all the opening & closing. Maybe a Chest style freezer & fridge, that does not let all the cold air spill out every time you open it ?

System2

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Wow!  Thank you so much for your rapid response - a sham(e) we didn't have you guys in charge of FEMA during Hurricane Katrina.

Here are some answers/responses to your questions/advise...

1)  My truck's kitchen is set up for propane; it powers only two appliances however - the deep fryer, and the 
     griddle/grill.  I understand the slow recovery of a propane powered refrigerator, and am happy with the electric, 5' Delfield
     already installed, although it is one of my biggest users - 1,500 W.  My freezer is an electric, 7 ft2 chest 
     variety.  I am financially hesitant to start replacing all of my electric appliances...

2)  If I were to limit the overall weight of a battery bank to around 1,000 lbs., what sort of power (amp hours) could I hope to
     get for that weight?

3)  There is one small (8" X 8") fanned vent on the roof of the truck, nothing else.

4)  Yes, I can park in full sun.


   I would like, for the initial set up of my operation, to simply start with a battery
  bank which I recharged by plugging it in to a 120 V outlet when at home - saving
  the solar part for when my business has shown sufficient success that I could
  afford that investment.

1)  What battery is right for my needs; what voltage?

2)  How many batteries would I require so as to not overly discharge the batteries?

3)  How long does it take to recharge these batteries; can it be done overnight?

4)  Can a battery be recharged on a 120 V outlet, and then at some later point using a solar charger?

4)  What other equipment would this AC recharging battery bank system require?

5)  How much would this all cost, don't forget I'd have to get the batteries, etc. to Maui?  How long?

Thanks again!!  I really appreciate your ideas regarding mitigating use of electricity to keep my power needs down.  With this mindset I might be able to drastically cut the size of the requisite battery bank to something much more manageable.


 

BB.

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

What you really need to decide is how much power do you need (peak in watts or kWatts, and how much energy you will need--kWattHours). Next, how much money you want to spend. And then, lastly, the type of battery technology--as a rough estimate:

http://www.rtpnet.org/teaa/battery.html

Energy Density

The amount of energy that can be contained in a specific quantity of the fuel source. Typically quoted in watt-hours per pound, wh/lb, or watt-hours per kilogram, wh/kg. For example, flooded lead-acid batteries generally have about 25 wh/kg, the latest advanced lead-acid designs claim about 50 wh/kg, and newer battery technologies such as NiMH and LiON are in the 80-135 wh/kg range.

So, if you needed 9kWatts for 6 hours, that would be 54kWhrs per day. From the above, a standard lead acid battery would weigh:

Battery Weight = (54,000 WH /( 25 W/kg)) * 2.2 lbs/kg * 1/50% (only use 1/2 of lead acid battery for good life) = 9,504 lbs.

However, if you only used 9,000 watts a total of 36 minutes per day (10% duty cycle), you would only need 950.4 lbs of batteries.

So--sizing a battery bank (and by extension, solar panels, generators, fuel tanks, etc.) really needs exact energy usage (and you need to conserve as much as possible to keep battery and solar panels as small/cheap as possible).

The only way you could probably use any significant amount of solar power would be to install a Grid Tied solar panel array at home/corp. yard (Grid Tied is where you have a solar power DC to AC inverter the "turns your meter backwards during the day"--or "net metering").

Another possibility, if you are in a fixed location for those six hours, perhaps you can talk with the property owner to put a "solar panel" covered patio over or next to your truck. If the location is not near utility mains, then you could use batteries (your truck and/or at the fixed shelter)--if there are utility lines, you can set a grid-tie solar power system right there (of course, it needs to be a secure area or you will have vandals throwing rocks and stealing copper/batteries).

Standard lead acid batteries are heavy--depending on how much energy you need with a limit of 1,000 lbs--you may have to look for a more expensive technology.

In terms of charging, you should be able to charge overnight without any big issues... Really depends on how deep you cycle the batteries and the type of batteries you have--but I would not worry about it at this point in your project planning. If you were open 20 hours a day and only had 4 hours of down time--that could be more of an issue.

-Bill

crewzer

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Shimyapu,

It’s not necessary to resort to large type and bright colors. That style of emphasis suggests that you’re shouting.

I can understand your reluctance to consider buying new appliances. However, as we go though this exercise, you may  ultimately find it cheaper to do so than to try and power everything from PV and batteries. Nonetheless, let’s address some of your questions directly. There are many possible solutions. 12 V is popular approach for automotive- and RV-type applications, and you may be able to help charge the batteries from the truck engine’s alternator, so let’s use that as an example.

Six size 8D batteries and a big inverter would weigh ~1,000 pounds. Wired in parallel, the battery bank would be good for 12 V x ~1,500 Ah, or 18,000 Wh. It’s not a good idea to use more than 50% of a battery bank’s capacity, so you’d have 9,000 Wh of gross energy available. Assuming 90% inverter efficiency, you’d have ~8,100 Wh net energy available for loads, or enough to run a 1,350 W load continuously for 6 hours.

Gel VRLA batteries from East Penn (Deka and MK brands) are rated to provide 1000 cycles at 50% DOD. So, expect the batteries to last for ~4 years (5 days/wk, 50 weeks/yr) before they need to be replaced.

http://www.eastpenn-deka.com/assets/base/0919.pdf

The OutBack System VFX2812M is a 12 VDC to 120 VAC inverter rated at 2,800 W (2,800 VA, actually). It could power any combination of loads up to 2,800 W. It also has a built in battery charger that could be powered from "shore power". Assuming you use VRLA batteries and that you pull 750 Ah from them, you’d need ~12 V x ~833 Ah to recharge them. I estimate it would take the 2812’s built-in charger ~9 or 10 hours to recharge the battery bank.

http://www.outbackpower.com/Mobile&Marine.htm

Here on the mainland, the batteries are ~$250 each ($1,500 for six), and the 2812 costs ~$1,800. You’d also need big DC breakers, heavy cables and some electrical enclosures and other miscellaneous doo-dads, so figure on perhaps $4000  -- plus the “shipping to paradise” premium – to get started.

A 24 V option would be to wire the battery bank as 2 x 3 for 24 V x 750 Ah, and to use a 3500 W model VFX3524M inverter/charger. Costs are ~ the same. A PV array rated at ~2700 W STC and a pair of OutBack MX60 charge controllers just might keep the suggested batteries (fairly well) charged in your location.

Finally, note that most of us here are not associated with NAWS, the site owner/operator. We're volunteers that like helping others understand and embrace this technology. If you're looking for specific quotes and delivery estimates, you'll need to contact NAWS directly.

Does this help, and is the type of information you’re looking for?

Regards,
Jim / crewzer

System2

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Aloha,

So I made a lot of recalculations, came up with some new ideas regarding cooking, and food storage that mitigate energy consumption, and now have a bare-bones minimum requirement of energy.

10, 935 Wh per day

11 Kwh per day (6 hours of business)

Everyone's advise has been very helpful.


With this new energy calculation...

1)  Is it now feasible to meet these energy needs with a battery bank?, and if so...

2)  How?

Thanks again!

BB.

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Shimyapu,

Go back to Crewzer's post just above yours... He listed 6x 8D batteries for 9,000 watthours (9 kWhrs) of usable power (for good life)... If you want 11 kWhrs (11,000 watthours) it would be 6 batteries x 11/9 = 7.3 batteries (round up to 8)...

One of the things to worry about is battery access and venting (if you are using wet cell lead acid batteries). You will need to clean them and top off the water level, probably, at least once per month.

Sealed batteries (like AGM), don't have any method to refill them with water--so assuming that you don't overcharge them (good quality charge controller with temperature compensation), you can mount those anywhere. You would have to look up the specs. to make sure that they support the number of charging cycles as the ones Crewzer recommended.

-Bill

crewzer

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

So I made a lot of recalculations,

Shimyapu,

OK... then you just need to make a few more simple calculations to answer your questions. As Bill suggested, it's just a matter of scaling to get from the model I outlined above to meet your latest requirement:

Six 12 V size 8D batteries (~1,500 Ah total, ~18,000 Wh total, ~9,000 Wh gross useable, ~8,100 net usable to ~50% DOD)

(10,935 Wh / 8,100 Wh) x 6 batteries = ~8 batteries, or:

Eight 12 V size 8D batteries (~2,000 Ah total, ~24,000 Wh total, ~12,000 Wh gross, ~10,800 Wh net usable to ~50% DOD)

Eight of these batteries plus the inverter would weigh ~1,300 lbs or so. The 2812 might have trouble recharging a 2000 Ah battery bank overnight (> 1,100 Ah required), so, at this point, you'd probably want to consider a 2 x 4 series/parallel battery configuration (24 V x 1,000 Ah, still 24,000 Wh total) and a 24 V mobile inverter. The VFX3524M is higher power (3500 W) and has a bigger charger than the 2812, but costs about the same.

Note that both the 2812 and the 3524 are "vented" inverters, so you may want to keep them away from airborne solids in the mobile kitchen environment.

HTH,
Jim / crewzer

System2

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Thanks yet again.  I had already made the following calculations... (and it looks like they follow your model)


12 V  X  2,037 Ah  =  24,446 Wh

24,446 Wh  /  50% (safe battery discharge)  = 12,223 Wh

12,223 Wh  X  90% (inverter efficiency)  =  11,000 Wh

So… 2,037 Ah are needed from batteries to provide the 11 Kwh required.

BATTERIES

1) Concorde Lifeline AGM  GPL-8DA
                255 Ah  X  8 Batteries  =  2,040 Ah
                8 Batteries  X  $450  =  $3,600

2) Trojan 8D-AGM
                230 Ah   X 10 Batteries = 2,300 Ah
                10 Batteries  X  $470  =  $4,700


My latest questions...

1)  Are there other specific batteries which I should consider for my purposes?

2)  Are there better prices?

3)  How might I be able to use the truck's engine/alternator to charge these batteries?  I read that the Lifeline batteries
     can be recharged extremely fast, if you have a sufficiently powerful charger.

4) It was mentioned that perhaps the Outback VFX2812 inverter wouldn't be able to recharge the bank.
Is this solely a time issue? Do you think 14 hours of charging would be sufficient? How do you calculate this?

5) Is there any reason why I should use the VENTED inverter over a sealed one? As was pointed out, I'm preparing food.

5)  As far as connecting the batteries... I read about using BUSS BARS, instead of wiring the batteries directly to one
     another... "Each battery in the bank receives the same charge current and discharges the same amount
     of current without having to pass that current through other batteries in the bank." 
     What are your thoughts concerning this issue?

Many thanks!!

mike95490

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Shimyapu wrote:

So… 2,037 Ah are needed from batteries to provide the 11 Kwh required.

5) Is there any reason why I should use the VENTED inverter over a sealed one? As was pointed out, I'm preparing food.

5) As far as connecting the batteries... I read about using BUSS BARS, instead of wiring the batteries directly to one
another... "Each battery in the bank receives the same charge current and discharges the same amount
of current without having to pass that current through other batteries in the bank."
What are your thoughts concerning this issue?

11 KWH will never make it from your vehicle alternator. Assume it's an 80A @15V = 1200W or 1.2KW for an hour of running.
A typical 115V 15A outlet, can supply 1725W, or 1.7KW in 1 hour. You'll need a little less than 8 hours to recharge from a wall outlet. If you can find a 230V outlet, @ 30A, you could cut that to 4 hours - maybe 5, to accommodate the slow top-off charge.

VENTED is usually smaller, but it will have cooling air moving past it , and you know how gunky the screens over your cooktop get !! you don't want that gunk to build up in your inverter - it does not fit well into the dishwasher.

BUSS Bars With high currents, even Buss Bars will have a finite resistance, and the batteries won't evenly share the loads. You need heavy cables/Buss bars, and then look at the diagonal wire digrams on how to connect.

BB.

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Another problem with a bus bar only type system is that you don't want road vibration shaking/twisting the batteries, terminals, and bus bar mounts. As long as you have good mounting and flexible interconnects so that stresses don't arise--either cabling or cabling with bus bars should be fine.

Obviously, venting of your battery box (especially if you use wet cell batteries) is important so that you don't get hydrogen gas (or acid fumes) near your cooking and electrical equipment.

-Bill

Brock

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

) How might I be able to use the truck's engine/alternator to charge these batteries? I read that the Lifeline batteries can be recharged extremely fast, if you have a sufficiently powerful charger.

Also with a larger inverter like this you will want to go with a 48v setup or you will pay a couple hundred for battery wiring alone. This basically rules out using the 12v from your alternator as well.

4) It was mentioned that perhaps the Outback VFX2812 inverter wouldn't be able to recharge the bank.Is this solely a time issue? Do you think 14 hours of charging would be sufficient? How do you calculate this?

Yes it’s a time issue. Assuming you pull 9kw out of the bank you have to use about 10kw to get back to full. If it can charge at 1kw an hours that’s 10 hours. Really a larger inverter that could charge faster would only help if you are somehow going to connect to a larger plug, like a 30 RV receptacle. A regular 15 amp 120v plug like you see everywhere won’t get you much more then 1.5 kw continuos.

I would also recommend using wire rather then a buss bar for movement reasons.

I have been wondering though. If your charging from the grid your still using power from the power plants over there. Also you will typically use about 20% more power this way and towing an extra 1500lbs around in your truck is going to add to your overall fuel usage as well.

BB what was a gallon of gas? About 10kw?

So you could carry 24kw of batteries, a good sized inverter or a 50 lb small quiet Honda EU2000I (inverter genset), $1k at most. I am just trying to be practical.

BB.

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Using the Honda eu2000i spec of 1.1 gallons for 1,600 watts for 4 hours or 1.1 gallons of gas for 400 watts for 15 hours, that gives you about 5.8 kWhr per gallon (at 1,600 watts) to 5.45 kWhrs per gallon of gas (400 watts).

Basically, around 2 gallons of gas per day would power your requirements. I am sure that there are other generator sets that would do a bit better... The problem being you don't want to oversize the motor/generator (a 10 kW genset putting out 400 watts 80% of the time would probably use much more fuel than a 1,600 watt set providing 400 watts).

You could get a nice RV/industrial unit that runs on propane (much safer--low CO emissions--if properly maintained and ventilated--and cleaner engines. Used on forklifts for inside buildings).

There are alternator sets (used for semi-trucks, industrial) that could be mounted to your truck's engine--however, unless you have a very long commute, it is not going to be very energy efficient (oversized engine at high idle, fan belt losses, etc.). I am assuming that your drive is not that long--put the money into either a good charger/connection at home and/or a dedicated genset (like a high quality, low rpm, RV unit). The Honda euX000 family is nice--but if this is a long term business (more than just a few tourist seasons), it is probably not what you will want for long term use.

You can certainly use a mixed-mode type of operation... Use 1/2 the number of batteries and only crank up the generator during peak periods (hybrid like operation).

I understand your desire for green operations--But you might look at other methods that achieve off-sets. Grid Tied Solar at home (placard on van noting Grid-Tie offset of energy usage), use your fry oil (and other mobile/fixed fryers of your neighbors) to setup Bio-Diesel (either for powering your truck and/or a local Diesel Genset). Sponsor green projects with x% of the gross or net to reforestation/alien species removal, etc.

-Bill

crewzer

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Shimyapu,

1) other batteries? I’d check into VRLA batteries from East Penn. Their brands include Deka and MK. See: http://www.eastpenn-deka.com/assets/base/0919.pdf and http://www.mkbattery.com/images/lagm.pdf

2) Are there better prices? Prices can be all over the map. You’ll need to check around with distributors and battery warehouses.

3) How might I be able to use the truck's engine/alternator to charge these batteries? Assuming the truck’s alternator is a 12 V model, it’s likely too small to make a dent in charging a 2,000 Ah battery bank. However, you might consider installing an after-market alternator and charge controller from Balmar (www.balmar.net).

4) It was mentioned that perhaps the Outback VFX2812 inverter wouldn't be able to recharge the bank. Is this solely a time issue? Do you think 14 hours of charging would be sufficient? How do you calculate this? If you take 1,100 Ah out of the VRLA battery bank, you’ll need ~1122 Ah to recharge ‘em. The top 20% of the recharge (10% of the total battery capacity) will take ~ four hours in absorb mode after a 50% discharge. The initial 80% of the recharge (898 Ah) will take ~7 hours assuming the 2812 can deliver its full 125 A charge current during the bulk stage. That’s an optimistic 11 hours minimum for both stages.

5) Is there any reason why I should use the VENTED inverter over a sealed one? The vented inverter/chargers can deliver more power to the AC loads and include a higher power charger. Check the specs for the various inverter/chargers.

6) As far as connecting the batteries... BUSS BARS… What are your thoughts concerning this issue? It’s important to balance charge/discharge currents in batteries. I think buss bars might be difficult to use in a large bank of 8D batteries. However, one option would be to have a pair of big buss bars and wire each battery to the bars using same size and length cables for all the batteries.

HTH,
Jim / crewzer

System2

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Thanks to all the advise I've received on this forum, I've given my project a lot of thought.

Bill's advise regarding the Honda generator has given me much food for thought...

1)  Is there any reason why I wouldn't want to buy two (2) of the Honda EU2000i generators and use a parallel connection AS OPPOSED TO buying the Honda EU3000is? 

Two of the EU2000i generators cost roughly the same as the EU3000is.

2)  With a parallel connection could I hope for the full 4000 W surge power?

3)  Are there any known problems associated with
     A)  these generators?
     B)  using these generators in parallel?

Thanks again!

BB.

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Shimyapu,

The Honda eu3000i has electric start. The eu1000i and eu2000i are manual start only. None of the eu family generators are really designed to be installed in a fixed installation (side of truck). I don't believe any of them have oil filters and probably would not be recommended for continuous daily operation--although they are probably some of the most fuel efficient/best quality/longest running "inexpensive" gensets out there.

Since the eu family is an electronic inverter design, they are very frequency stable. Great for electronic and motors--mostly wasted on incandescent lighting and heaters. The 4,000 watt surge with two eu2000i units should be real and work fine (you may need to have the motors set to high speed instead of the variable speed fuel conservation mode to handle the surges cleanly).

The Parallel Kits for the Honda eu's are not anything fancy (from what I have read). Just connecting the two outputs in parallel and adding a (unneeded?) circuit breaker.

Using two generators in parallel continuously is probably more costly than using a single larger generator (maintenance costs, wear and tear).

If you are looking for a short term solution--the Honda eu's would be nice (the are very quite and clean running--when in tune)--assuming they support your electrical requirements... However, if you are looking for a long term solution--you need to look for a commercial service rated genset (I used the Honda's as an example to compare the approximate available energy in 2 gallons of gasoline (12 pounds) vs 1,200 lbs of batteries--was not suggested as perfect solution for your needs--as I don't really know your needs well--just guessing).

If you like the Honda's for your needs, there is a method that folks use to support longer run times (more than the on-board fuel tank alone). Basically, they put new fuel caps on the generators with a plastic tube to a 5 gallon plastic fuel jug. The Honda's are able to siphon fuel from the larger tank.

Here is a link to one of those systems (seems to be over priced--but people do buy these kits rather than trying to build their own)--Wise Sales is also one of the sites that people continue to recommend for buying the Honda Generators from too (low prices, good delivery and service):

http://www.wisesales.com/DurationTanks.html

-Bill

System2

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Regarding the Honda EU3000is, I own one and it is incredibly dependable. It's tough to get a deal on them though; most dealers told me they make very little if any profit on them. I think I paid $1,799 plus tax in Phoenix in the fall of 2007. You can't go wrong with Honda. Good luck!

System2

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Aloha,

Anyone - I would like to know if anyone could help me get started with my thesis: A COST-BENEFIT ANALYSIS TO “GO GREEN” FOR A LUNCH WAGON BUSINESS.

Shimyapu - I would like to hear what you came up with and how much it costs you overall.

Here's my problem statement:

The owner of a small “lunch wagon” business in Hawaii wants to do everything possible to ensure that he operates using environmentally sound business practices. This includes ensuring that products used in his daily business operations are environmentally friendly. It is his intent to make sure those items such as plates, cups, and plastic utensils are replaced, when possible, with the latest in “green technology”. Other areas where environmentally sound changes can be made will be identified as research continues.

However, the most significant area of operation to be addressed will be energy sources. Energy to run the truck and all of the food service equipment is the most costly aspect of the business and has the most notable environmental impact. Things such as refrigeration, a cooking grill, and appliances used for daily operation require some source of energy. The energy sources may be electrical power or some form of gas.

In recent years, alternative energy sources have become viable and available on the market. Solar power is now a viable and environmentally friendly source of energy. In addition there are new products capable of storing energy in a scale that may be sufficient to use on a catering truck. Many other newly developed products are on the market that may be compatible with energy needs of the business, including new fuels that may power generators when solar power is not sufficient or available.

Since this is a business, the costs of acquisition and installation must be weighed against the benefits. Those benefits may be tangible and intangible. If the cost of converting his truck into an environmentally friendly operation can be offset by savings, then there is tangible benefit. However, there are intangible benefits for the owner in terms of sense of accomplishment and the personal pride that comes from knowing you took action on an important issue. He will have to weigh tangible benefits if they exist against intangible benefits in order to make a decision that satisfies business needs and personal goals.

This research might appear to be insignificant at first, however, if this research can show that there are potential green energy savings at this level, the potential for tremendous savings exist for large applications.

Operations that require an energy source must be identified. Once that is accomplished, then research that identifies alternative means can begin. As products are identified, it must be determined if they are viable for use in a catering truck. Any products that are selected must be researched in enough detail to determine if they can produce the energy required by the operation before going further. Once a product is determined to be viable, then associated costs and operational savings can be calculated in order to determine if there is any tangible benefit.

These questions must be answered:
• What are the current energy requirements of operating the truck?
• Are there products that have been developed that can replace all or part of those energy needs?
• What are the costs associated with those products in terms of acquisition, installation, and “downtime”?
• What are the benefits associated with the replacement of any energy source?
• Is “going green” a viable option for a catering truck business?

MAHALO! (THANK YOU!) ... Venus

niel

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

in my opinion, there is a limit to what you can do in "going green" for an energy hungry lunchwagon. you won't be energy independent and you won't stop creating co2. the best you could hope for is to make a small dent in those requirements for the lunchwagon and hope that the public is uninformed enough to buy that as a selling point of yours that justifies the higher costs you'll charge your customers for the same products without the go green overhead costs. if you do it, do it for you and eat the costs, for passing those costs down to the customer may put you out of business.

mike95490

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Likely the "best" way, is to build a hurrricane & vandal resistant carport, roof it with solar cells, and via Grid Tie, sell back to the local grid. Photograph that, and paste it to the side of the truck.

Lunch truck can't carry enough PV to run one fridge, or boil oil for fryer. You could maybe get enough PV to fit, to run vent fans with it. The weight of batteries, added to all the other gear in the truck, and the tires will pop.

BB.

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

The above posts pretty much define the issues. And not much has changed in the last few years.

Are you writing a paper for school--or trying to start a business?

-Bill

System2

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Bill,

I am working on a Masters thesis that is based on a Cost-Benefit Analysis of applying "green" technology to the operation of a lunch wagon. I am looking at all aspects from using biodegradable packaging to using clean energy sources such as solar recharged batteries, LP refrigerators, etc.

I came across this thread during some research. I found that Shimyapu was asking the same questions that I might ask, however he needed the technical answers since he was actually in the business. I am simply trying to discover what is possible to do and what would it cost.

I am doing an analysis that simply answers the question, "What can be done to "green" a lunch wagon and is it cost effective?"

If you have the time to offer any information, I would be very grateful.

Thank you. Venus

BB.

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Shimyapu seems to also made a few posts over on this catering board. You might find him and some others that can help you with their point of view.

Basically, mobile food services has several strikes against it regarding "going green".

1. Cooling and cooking temperatures and the equipment, are regulated by government polices... So trying something "non-standard" is going to be looked at closely--and may affect insurance too.
2. Keeping cold food cold can be helped with ice and insulation. But getting cold food hot is an energy intensive endeavor. And, you have to be able to do it at any time (usually rain or shine, day or night). So--you need energy on demand.
3. You can look at ways of getting the heat more efficiently to the food (microwave, steaming, frying, grilling, IR+convection oven, etc.) and you can look at improving the efficiency of the heating devices (insulation, reflectors, better control of heat, etc.).
4. But, in the end, you need a concentrated energy source. You can read through the above thread, but a 1/2-1 ton of batteries can store about the same amount of useful energy as 16 lbs of gasoline (even allowing for the poor efficiency of a gasoline generator).
5. To use captured solar energy requires large capture area... Full Sun is about 1kW per m^2 (high noon). But collection efficiency (for electricity) is only about 10-15% for PV electric panels. You can collect hot water at ~80% efficiency--much smaller collectors for the same area... But if you need the working fluid above 150-180F--you are either going to need a post heater or high tech vacuum thermos bottle collector technology.
6. And, in any case, you still need to store the energy for use on demand, and have a backup power source for poor weather, non-noon time, and peak loads.
7. Also, many times, in the "lunch wagon" business, your major consumers are more concerned about time, taste, and money. Most are not going to pay more for a (possibly perceived) lesser product/experience.

You might be able to make a nitch business with green methods... One person (was it here) was making/suppyling "star wagons" with solar power and such. But even then, it was not a no-risk business.

Another was a photographer that setup a battery powered still camera base station with a mast/tower to raise the camera above the crowd type shots).

Regarding the other "green" products (plates, forks, soap, etc.)... Last year going through some national parks, found they were using (and advertising use of) bio degradable "plasticware" and such. But I don't have much to offer--just googling is where I would start.



-Bill

System2

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Aloha Bill,

Thank you for all the insightful information and thoughts that you provided. You have been a tremendous help. While I really don't want to be a bother, your obvious expertise makes it hard not to ask for a little more help.

Would you be able to provide any specific product information regarding energy items that have been discussed, such as batteries, solar panels and/or complete solar energy systems, etc. If I have product names then I will be able to collect the cost data that's obviously critical to the analysis.

If anyone else reading this has information, I would very much appreciate your time.

Mahalo (thank you) again for all your help. Venus

System2

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Jumping late-
start with a power survey of the power you need and the functions of the power.
then evaluate each energy source as the amount of watts per type of energy source.
for instance you will fined that methane and propane have the greates watts for the resource.
then evaluate what can deliver the power you need for the function to be performed.
you will find inverters are very effiecent but max out at about 3KW.
Then evaluated Battery usage, like max amp draw and Amp hours you will find for 4 t105 you can run a 1kw microwave for about 1/2 hr before you have to charge the batteries for 4 hours at 60 amps.
there is no way you can run a cooking grill on stored power, so you need a countious power source like a generater, for elelctric, or propane for gas.
so lets say you go with a lithium batter pack like is use on hybrid buses.
they deliver 96KW for a period of 15 min before the engine kicks in to charge the batteries.
the price of such a battery pack is in the thousands.
I suggest you talk to a Transit mechanic to get the actual particulars.
So you could have a hybrid type vehilce that you tap the Lithium stack for everything. But you still running on propane to power the engine.

my 2 cents

BB.

Re: Battery Bank to Power Lunchwagon's Mobile Kitchen

Venus,

The host of this forum has their own website with about 95% of the equipment/parts needed to make a solar PV system. Northern Arizona Wind&Sun.

And, you can go through and pick and choose items--that may or may not work in a "real system"--but will get you kind of close to where you want to go...

However, and I am speaking as a real honest to god engineer who did pretty well starting with "blank pieces of paper".

1. Get a good idea of rules of thumb... Having an idea in the back of your head that xyz will cost $xxx,000 per abc units will give you a very quick idea of what will and will not work.
2. Understand the needs of the "customer" (Lunch Wagon owner and their patrons). It is not that difficult to define and assemble a solar RE system--what is hard is making one that will meet the customer's needs.
3. The customer is not always right... Customer comes in and says I need QWERT for $xxx,000. In reality, QWERT will not work well with renewable energy--is there a different thing that will work like QWERT but in the end process the food/etc. with similar (and acceptable) results using less resources? May not be...

So--you can use some rules of thumb to help customers understand that when the demand QWERT--there are a whole bunch of assumptions that go into that demand. Portable generators, Large Propane tanks, lots of noise and fumes. May be cheap to "buy"--but will cost 2-4x as much down the road for fuel. Etc.

My suggestion, treat the Solar RE as a black box for the first pass... Understand/Estimate the peak loads (i.e., maximum Watts) and the average loads (Watt*Hours) per day.

Work on reducing the power needs as much as possible. It is almost aways better to spend money/time reducing the power needs first (conservation) rather than trying to figure out how to generate more power later (for an inefficient installation).

And, this has to include everything... For example, refrigeration will be a large consumer of electricity. Parking under an awning or better roof insulation, better fridge/freezer insulation, more efficient compressor motors, etc. all help reduce the loads.

Some basics:

$0.10-$0.30 per kWhr: Grid Power
$0.15-$0.40 per kWhr: Grid Tie solar PV inverter (+20-50% tax credits may be available)
$1.00-$2.00 per kWhr: Off-Grid Power (solar+batteries+AC inverter)

Cost to build:

$1 per Watt: conventional utility power
$8-$10 per peak watt generated Solar GT (ie. 3,000 watt of solar GT; ~$25k-$30k)
$10-$15 per peak watt generated Solar Off-Grid (includes new batteries every 3-10+ years)

How much can a solar PV system generate:

Really depends on location, seasons, local weather conditions, area clear of shade (trees, buildings), type of system, etc.

Use the PV Watts Calculator to estimate monthly/yearly power output. Also has output hour by hour (details button). A system on the cost of Maine or in New Orleans is not going to generate as much power as something in Central Arizona.

For example; Honolulu, HI. Assume a 3kW CEC rated system (3.5 kWatts of Solar Panels--assume to cost ~$30,000 to install a grid-tied system in Honolulu). Assume a derating factor 0.77 for Grid Tied Power (array tied to local utility--truck plugged into utility). Fixed array, rest of data set to default:

Results for Grid Tied Solar Array

Month 
Solar Radiation(kWh/m2/day) (aka "hours of sun per day")
AC Energy (kWh)
Energy Value ($) (assuming $0.18 per kWhr)

1      5.01          381        68.96   
2      5.59          385        69.69   
3      5.89          448        81.09   
4      5.79          427        77.29   
5      6.00          456        82.54   
6      5.91          433        78.37   
7      6.02          455        82.36   
8      6.25          471        85.25   
9      6.41          467        84.53   
10      5.72          434        78.55   
11      5.16          380        68.78   
12      4.92          373        67.51  
================================================ 
Year 5.72 avg sun  5,110 kWhrs/yr $924.91 per year

Now, lets make one change--assume that this is an off-grid system (moving lunch wagon, fixed location in a park--but no grid power). Set the derating = 0.52 (assuming losses from batteries and additional power conversion inverter):

Results for Off Grid Array

Month
Solar Radiation(kWh/m2/day) (aka "hours of sun per day")
AC Energy (kWh)
Energy Value ($) (assuming $0.18 per kWhr)

1      5.01          251        45.43   
2      5.59          255        46.16   
3      5.89          296        53.58   
4      5.79          281        50.86   
5      6.00          300        54.30   
6      5.91          285        51.59   
7      6.02          300        54.30   
8      6.25          311        56.29   
9      6.41          309        55.93   
10      5.72          287        51.95   
11      5.16          251        45.43   
12      4.92          246        44.53 
================================================   
Year 5.72 avg sun  3,371 kWhrs/yr $610.15 per year

Just that one little change (Grid Tied vs Off Grid) makes a huge change in the amount of useful power generated...

And the Off-Grid system is even worst... It can only store a few days of energy. Any extra power generated outside of these 3 days or so is forever lost. Any peak power needed (because of cloudy weather) must be provided by an alternate source (generator, conservation, etc.).

A Grid Tied system with 1 Year Net Metering can effectively "store" (or even borrow) electricity over a 1 year period.

There are lots of way of looking at/for a solution to your problem statement--but, in the end, Solar RE is going to be a game of "inches"... At best, solar RE can usually offer only single digit percentage points of return... Gaining/loosing 30%-50% of power output due to system design/location or load requirements by the "kitchen" can swamp the ROI.

Taking tax rebates and credits (and local laws) into account usually is what will make or break the the cost/benefit equation.

-Bill